UNION CITY - Mayor Brian Stack, a Democrat, gave a full-throated endorsement of Republican Gov. Chris Christie today when Christie appeared for a ceremony marking the opening of the new Colin Powell Elementary School.

Stack, whose speech stopped short of endorsing Christie’s bid for re-election, called the governor the best he’s ever worked with.

“He’ll fight with Republicans, he’ll fight with Democrats – whatever is best for New Jersey,” said Stack. “In Union City, he’s Numero Uno.”

Christie is seeking a second term in office, and his likely Democratic challenger is state Sen. Barbara Buono, of Middlesex County. Stack, also a state senator, declined through his spokesman to say whether today’s speech extolling Christie was an endorsement of the governor’s re-election bid.